With Manufacturer's Scan Tool

Turbocharger And Charge Pressure Control Valve, Checking

Special tools and repair equipment required







- Turbocharger tester VAG 1397 A







- VAS 5051 with VAS 5051/1
or
- VAG 1551 with VAG 1551/3 A

Requirements
- All hoses and lines must be securely installed and free of leaks.
- Diagnostic Trouble Code (DTC) memory has been checked
- Output Diagnostic Test Mode performed
- Vehicle Diagnostic, Testing and Information System VAS 5051 or VAG 1551 Scan Tool must be connected.

Work sequence

WARNING:
- Always attach testers and measuring instruments to back seat and have them operated from there by a second person.
- If testers and measuring instruments were to be operated from front passenger's seat, person sitting there could suffer injury in the event of an accident due to triggering of front passenger's airbag.







- Connect T-piece and measuring hose of turbocharger tester VAG 1397 A to intake manifold (front).
- Route measuring hose under rear edge of hood and into passenger compartment via right side window.







- Switch on turbocharger tester and set measuring range selector switch to position -I- (absolute pressure).
- Connect measuring hose to connection -I-.

NOTE:
- Hose connections must be completely airtight, otherwise measurements will not be correct.
- Ensure that measuring hose is not pinched at hood or side window.
- Pressing memory key -M- on turbocharger tester will store last measured value until memory key -M- is pressed again or tester is switched off.
- The decimal point in display flashes to indicate that value is being stored.
- If battery voltage of turbocharger tester drops below minimum level, an arrow will appear at top left of display.
- Before performing test, drive vehicle at brisk speed for at least 3 km without stopping (i.e. along route without traffic lights, etc.).
- A second mechanic is required to note readings on tester when vehicle is moving.







- Read measured value block, display group 115, engine idling.
- Accelerate vehicle from 2000 RPM to wide open throttle in third gear and watch rev counter.
- At approx. 2500 RPM, press "print" key on VAS 5051 or PRINT key on VAG 1551 while simultaneously pressing memory key -M- on VAG 1397 A.

NOTE: The charge air pressure should be measured using turbocharger tester VAG 1397/A. Vehicle diagnostic, testing and information system VAS 5051 or scan tool VAG 1551 is used to check whether charge air pressure is being registered by control module.







- Specification for VAG 1397 A: 1.500 to 1.600 bar







- Specification on VAG 1551 or VAS 5051 in display zone 4: 1500 to 1600 mbar

If reading does not match specification, troubleshooting table.

Malfunctions in charge air pressure control

Malfunction Possible cause of trouble
Charge air pressure below specification Wastegate bypass regulator valve -N75- faulty, checking Hoses to Wastegate bypass regulator valve -N75- faulty, connection diagram or, connection diagram
Charge pressure control valve in turbocharger sticking in open position
Leak between turbocharger and intake manifold, effects
Mechanical air recirculation valve faulty, checking
Recirculating valve for turbocharger -N249- faulty, checking
Turbocharger faulty, replacing
Charge air pressure above specification 1) Vacuum unit for charge air pressure control valve faulty, replacing
Hoses to vacuum unit for charge air pressure control (via -N75-) leaking, connection diagram or, connection diagram
Charge air pressure control valve in turbocharger sticking in closed position, replacing

1) If charge air pressure is too high, fuel supply will be interrupted in order to protect engine. This results in misfiring at high engine speeds.